Steam generating boiler



Jan. 3, 1950 J. MARlNl 2,493,673

STEAM GENERATING BOILER Filed March 18, 1944 Confrg/ lfa/re WATER 570m 65 I PRESSURE TANK 7- fill afar W Wv/er flip (y Patented Jan. 3, 1950 i STAT ES: v F] C E STEAM GENERATING BOILER 'John Marini', New York, N. Y.

v. .w Application March 18, 194}, Serial No. 527;!) 97 4'Claims. -(Cl. 122, 448) "My nv nti n relates n ments i steam generating.hoilers,"apparatus, or imits used to,

application, or heat to the, liquid in a closed vessel.

1 At presen most. steam ne n boilers pend (in. thelnatural; tendency ofheated water to rise above the coolerwater in thefsystem to create a flow'orcause circulation of water in. the boiler. The speed.iwithIwhiclilthisvcirculating water flows over the heating surface of the boiler determines the amount orheatnwhich the heating surface cans'aiely transmit, periunit area of heating surface, to. the water without forming steam pockets r'smtantoyerheatinQ and failure of heating surface metal. l. .Furthermore-thesteam as generated in the. ordinary steamboiler is very nearly Wetaiid an lextral-unit usually called a superheater lis ernpldyedto change the quality ofrthe steam as required.

witlnmyi inventionrtheifiow of water over :the heatfmgg surface =01 the boiler. is controlled so that rii'oreheat per area of heating surface can he safely transmitted to-the boiler water without verheatineendia lu e-Qahea ine surfac ofthe bQilenthereby makingthes-team boiler more compact. Furthermore thenquality ofthe generated steamscan be changed-without the: use ofextra unitsrsuch as superheaters. L---Ihe ohiects -a nd advantages of my invention will be apparent' i'romslthe' accompanying :drawing.and following; detailedzdescription.

.l The single drawing .is at schematic, partially dia rammatic; "view :ofzone form f my-inventio tor-a steam generating boiler.

HInview ofcthef. fact; that standard units.- such asieontrollingivalves; check valves;v water pumps and-"various pressurecontrol/and waterlevel control devicesrinay be. :employed with my: invention andzthatx sucha devices individually" are: available inanany' iimclified"dorms;- for purposes of clarity and lsimplicityithesedevices will not -be described inzdetailibut wilt merely be referred to in terms otetheirizfunctiorr since their-"varied forms -'--ar e wellfknown the attend-the operation of 1 the steam generatingiboiler; unit, or apparatus using myinventiomis not dependent upon any specific form of such units.

Referring in detail to the' one-drawing which ilhistratespne form of my-inventlon as applied to a steam-generating boiler, T is a water reser-' voie;which'-I call the'water storage pressure tank, containingwater-*under a" constant predetermined pressure which is being discharged through pipe= line 1 and being-forced under pressure from the water storage pressure tank T in a relatively restricted---'st ream through a generator such as generator coils G1 and G2, inexcess of that required to meet a steam demand, where saidstream ofwater-is heated then flows" through pipeline 2 tea control valve H Which-controls crregulates the rate of discharge QtithiS heated stream of water into a closed vesselF which I call the hash am er; wh te m s. epa o the xcess-:unvaporizedwater at a desired constant pressure which is lower than the pressure onthe Wa rl ne i eline 21 h? generator oil G1 M16162, and the water. stgragempressure. tank T. .The steam is withdrawn fror'rrthe upper portion of the flash chamber F through a steamoutlet such as .I to, meet/the steam demand .whilethe excess unvaporizedfwaterifalls to the bottom of the flashchamber. and .tends to accumulate and form intoa body of ..water. therein which I call accumulated water. Thisaccumulated water is withdrawnirorn/the ,flash chamber F by alpump B which. raises the. pressure on this accumulated waterlandldischarges this Water through pipeline 3 intothe. water storage pressure tank T to be. recirculatedv through the generator coils G1 and G2. A pump A supplies ieedwater under pressure to. the water storage pressure tank T insufficient quantities to maintain the water contained therein under the v, :=constant predetermined pressure. The accumulated water ,and'the, feedwater com-1 binein the water storage pressuretank T to form the water contained therein.

;.t'I he:.generatora-shown in=the-drawing is made up of two tubes in; the form of coils G1 andGa. connected:- for: parallel flow, through which :the water is-iorced and heated; =The generator, can bem-ade up of; either asingle; tube or of= any number of tubes'z-connected for series or parallel flow -whichwdue to the forced water circulation, can be- -bent inalmost anyzconvenientsshape to. obtain efiicient; heating 1 of l the iwater; Whileany source 0f::heat can be used tofurnish heat to the .agenerator'coils Grrand Grwithout departing from; the spirit of theinvention, an 'oil burner L is :shown onithe drawing in this regard which receives its supply of fuel oil through the regulatingtor controlling valve'M. Valve M therefore represents-the means to-"regulate or controlthe heat input to-the generator coils G1 and G2.

Thge-fnnction of the generator; shown on the drawing asgenerator coils G1-and Gz; is to sufficientl-y-heat thestream of water, being forced there throughunderpressure, to cause a portion of said stream to flash into steam and separate from the excess unvaporized water when the heated stream of water is discharged from said generator coils G1 and G2 into the flash chamber F wherein the pressure is lower than the pressure under which said stream of water was heated in the generator coils G1 and G2. It is to be understood that for some operating conditions a certain amount of steam will be generated in the generator acoils' G and G2, however such steam as is formed in the said generator coils G1 and G2 will remain in intimately mixed relation with the water andin no case will any separation I is to sep- 1 chamber F together with any steam formed partially in the generator coils G1 and G2, from the excess unvaporized water and enable the steam and the excess unvaporized water to be with; drawn from the flash chamber F independently of each other. The flash chamber F is aclosed vessel capable of withstanding pressure. The upper portion of the flash chamber F comprises a steam zone into which the stream of heated water from the generator coils G1 and G2 is discharged through the control valve H. In the lower portion or on the bottom of' the flash chamber'F the excess unvaporized water accumulates and forms into the body of accumulated water.

j Steam' is, withdrawn from ,7 the upper ,portion of the flash chamber F'through any suitable means such as the steam outlet I to meet the steam demand. a

f The accumulated water is withdrawn from the flash chamber Fin such quantities as to maintain the surface level ofthe bodyof accumulated water between 'a predetermined high level and a predetermined low level such as is represented by ,V and W respectively on'the drawing. The difierence between the surface water levels V and W can be made so small as to be infinitesimal in which case the surface level of the body of accumulated water can be maintained at a desired predetermined level.

" Pump B withdraws the accumulated water from the lower portion of the'fla'sh chamber F, raises the pressure on this water, and discharges this water through pipeline 3 into the Water storage pressure tank T to be recirculated through the generator coils G1 and'Gz. Connected with'the' flash chamber F is a liquid level controllerb, which can be of the type as manufactured by theBrownInstrument Co., to so control the operation'of pump B as to maintain the surface level 'of' the body of accumulated water in the flash chamber F between the predeter; mined'levels'v and W. The pump B can be of any desired t'ype anddriven by any convenient drive'means such as an electric motor.

' The primary function of the water storage pressure tank T is to provide a reservoir of water being maintained under a constant predetermined pressure for subsequent forcing through the generator coilsGi and G2 under pressure from the water storage pressure tank T. Another function of the water'storage pressure tank T is to make possible the recirculation of the accumulated water from the flash chamber 'F through the-generator coils G1 and G2 without f rst reducing the pressure on saidaccumulated water. while at the same time maintaining the r 4 water in the water storage pressure tank T under the constant predetermined pressure. Still another function of the water storage pressure tank T is to permit the addition of the feedwater to the accumulated water while under the constant predetermined pressure in the water storage pressure tank T which pressure is higher than the pressure on the accumulated water in the flash chamber F. It is to be noted here that as a :general rule the feedwater 'ingsimilar type boilers is either added tOJth'eKaccumulated water while in the flash chamber F or is added to the accumulated water while under reduced pressure.

'lated water while in the flash chamber F then thefeedwater must be preheated to the exact If the feedwater is added to the accumutemperature of the accumulated water contained therein to prevent'cooling of the body of accumulated water in the flash chamber F and also cooling of the flash chamber F with an appreciable loss of the steam available to..meet, the

steam demand. If the pressure on thef accumu l'ated waterfis reduced before addition or the" fe'edwater then ebullition of" the accumulated water occurs as the pressure 'is reduced unless a heat exchange system is added to prevent loss of heat by the accumulated waterdue to said ebullition,furthermor'e in this case there'is the: additional loss of energy required to raise the pressure on the accumulated water back up to the original pressure on flash chamber F.

a water reservoir bounded by, a'closed'container,

such as a tank or pipe, wherein the accumulated water withdrawn from the flash chamber F- and the feedwater combine to form the water being maintained under the constant predeterminedpress'ure, for subsequent forcing through the A generator coils G1 and G2 under pressure from the water storage pressure tank The primary function of the pump A'is to raise the pressure on the feedwater suflicientl-y high to force said water into-the water storage pressure tank T. I The opemusn of the pump A iscontrolled by a pressure controller a respons ive to pressure in thewater storage pressure tank T. "Pressure controller a can be any pres sure operated-control device such 'as a Brown'- Instrument Co. pressure' co'ntroller model 7085- 810. The pressure controller a controls the 'operation of the pump'A for theforcing of sufiiient' quantities of'the feedwater into the water stor-- age pressure tankT to maintain the water contained therein under the constant predetermined pressure while said water storage-pressure tank same time dischargesathe water contained therein under pressure throughthe generator. coils G1 and G2; Byi forcing sufficient quantities of the feedwater into-the water storage pressure tank T to maintain the water contained therein under the constant predetermined pressure, suf-' ficient feedwater is'thereby added to thewater contained in the water storage pressure tank T to also maintaina substantially constant quantity of the water contained therein alwaysavailable for forcing through the generatorcoils, G1 and Gz and to compensate for. the water in the form of steam being withdrawn through the steam outlet I to meet-the steamdemand; The, pump A maybe of any desired type'and driven by any convenient means such as an electric said water while in the aaaaors 5 While I mrefer add all of the :Ieedwater to the accumulated water while in the water storage pressure tank (T9 as shown, the invention 7 is mot limited thereto. For some operating conditions it possible to add a portion 'of the feedwater to the :accmnulated water while in the hash chamber without departing from the snirit of the invention, in which case .pump (A adds the remaining portion of. the feedwaterto the accumulated water in suificient quantities to maintain the water in the water storage pressure tank 31, under the comtamt predetermined pressure. r C is an air chamber connected to and communic'ating with the water storage pressure tank One infliction of the chamber C is to provide an air cushion to yield to "the forcing of the accumulated water into the water storage pressure tank Another function of the air chamber C is to allow sufl'icient reedwater to be *iorced into the water vstorage pressure tank T to maintain the water contained therein under the constant predetermined pressure while the last mentioned water is being discharged.

or the accumulated water. i

There are three pri-nciples of operation on which this steam boiler can operate to gen-- erate steam. The first two principles of op eration are distinctly di fieren't from each other and the third principle of -operation is a combination of the first two principles.

" The first principle 50f operation employs a control valve, in place cr me control valve H shown on the drawing, of a type which allows a constant predetermined rate of discharge "oi the "heated stream of water, flowing from the generator coils G1 and G2, into the flash chamher '15. 'A control valve of the type mentioned can simply consist of an orifice or can consist of a valve which can be adjusted and set to allow said heated "stream 'of water to: dischargeinto the flash chamber F at any one ofa number *of different rates "of constant discharge. Once the constant 'rate of discharge of the heated "stream of water flowing from the generator 'co'i'ls G1 and G2 into the flash chamber? is determined and fixed, the steam available to meet the steam demand is controlled by the heat input 'to the generator coils G1 and G2. "The greater the heat input to the 'generator coils *G1 and Ge the greater will be the ratio of steam separated to excess unvaporized water when the heated stream of "water is discharged into the hash chamber "F and vice versa.

A "pressure actuated device h, responsive to pressure in the flash chamber F and connected thereto, is 'operatlve'ly connected (not shown on the drawing) with the'valve M which controls the heat input to the generator "coils G1 and The pressure actuated device h-can be of the 'type as manufactured by the Brown instrument G0. and named-a "throttlor controller? The -pressure "actuated device 'h is set to maintain the desired pressurein the ilas'h chamber F. when the steam demand is B and measure in the dash chamber F-temis (to :fall below the desired pressure, we device 72. causes :valve. M te the zheait input to the generator -coils G1 and G2 and thereby hicrease the ratio of steam separated to excess unvaporizo'd water to ea-use sufficient steam to be separated in the dash chamber F ito meetliilre demand maintain the desired pressure therein. When the steam demand eclecreases and the pressure the flash chamber F tends to increase above the desired pressure theldevice .72 causes valve iii! to decrease the heat input :to the generator coil-s G1 and thereby decrease the ratio of steam separated to excess kunvaporized water to cause a reduction of the steam separated the chamber 5! andmain taiin the desired pressure therein.

The first principle of operation thereIor-e to discharge the heated stream "of flowing from thegenera'tor UdilSGl and G2 into the hash ola-amber F at-a constant predetermined rate and to-vary the heat input-to the generator coils G1 and G2 according to variations of desired pressure in the flash chamber F, caused by variations in the steam demand, to cause the ratio of steam to excess unvaporized water separated in the flas'h chamber "F "to vary such a manner astornake available suflicient -'steam to mee'tlthe varying steam demand and maintain the desired pressure in the flash chamber The second principle of operation employs a control valve H of a throttling type which varies the rate of discharge of the heated stream of water, flowing "from the generator 'coi-ls and G2, into the flash chamber iAny "throttlin g' type control valve can be :used without i (such as "shown on the drawing) or otherwise is made between the throttling type'wntrolvalve-H and the walvefM to cause the heat input .to the generator coils G1 'and'to vary'w'ith-the rate of discharge of the heated stream of water, flowing from thegenerater coils G1 and'Gafiinto the flash chamber :F. This connection is so adjusted as to :cause' the ratio of steam to 'excess-unvaporized water'separatedin the flash chamber F to remain at a predetermined fixed value irrespective of the rate of discharge of the heated stream of water rlowingrrom the generator coil-s :G1 and G2 into the flash chamber F. Consequently, the greater the rate of discharge of said heated stream 'of water -into the flash chamber F the greater the heat input to the generator coils G1 and Grand vice versa.

'The'pressure actuated device it is now operatively connected with the throttling type control valve'H andtherebyinterconnected'withthe connection *b'etween the throttling type control valve H and the valve "It is to he clearly understood that the 'pressure actuated device h con-- trols the opraitionoi said connection regardless of how the device it may be-connected or interconnected "with said connection. "The pressure actuated device 11 is set to maintain the desired pressurein the-flash dhamber F. When thes'team demand is increased and qaressure in the iflash chamber F tends to fall bvlow the desired pressure the device h causes throttling type control 75 valve iboincrease therate-ofdischarge of the heated stream of water flowing from-the generator. coils G1 and G2 into the flash chamber F and at the same time causes valve M; which is connected with the throttling type.:control-;valve H, to in-, crease the heat input to the generator coils G1 and G2 sufficiently to maintain the ratio of steam to excess unvaporiz'ed water separated in the flash chamber F at the predetermined fixed value. .By;

allowing more of the heated water to be discharged into the flash chamber F more steam is separated and made-available to meet; anjn-l crease in the steam demand and maintain the desired pressure in the flash chamber F. When thesteam demand is decreased and the pressure in the flash chamberF tends to increase above the desired pressure, the device h causes the throttling type control valve H. to decrease the rate of discharge of said heated stream of water flowing into the flash chamber F, and at the same time causes the .valve M to decrease the heat input to the generator coils G1 and Gasufliciently to. cause a reduction of the steam separated in the flash chamber F and -maintain the desired i pressure therein. v

The second principleof operation therefore is to maintain a predetermined fixed ratioof steam to excess unvaporized water separated in the flash chamber F while varying the rate of discharge of the heated stream of water flowing from the generator coils G1 and G2 into the flash chamber F in order to meet a varying steam demand and maintain the desired pressure in the flash cham: ber F. r I

The third principle of operation employs the throttling type control valve H andthe connection between the throttling type control valve H and the valve M as with the second principle of operation except. that instead of the connection between the throttling type control valve Hj and the valve M being'adj ustedjto obtain'a predetermined fixed ratio of steam to excess unvaporiz ed water separated in the flash chamber F as 8 pressure is fixed and does'not-change'. If the steam boiler is. to supply steam-at 200 lbs. per sq. in. pressurethen this 200 lbs. per sq. in. pressure. is the desired. pressure to be maintained in the. flashchamber'F at all times. Howevenonce the desired :presSureltobe maintained in the flash chambenFis known, the pressure under which the wateris being maintained in the water storageupre'ssurei tank .T-must be deter-. mined. As can be easily :seen there .are any numberof pressures .under which the water contained in the water storage pressure tank T can be maintained. The higher the predetermined pressure under whichthe water'contained in the Water storage pressure tank T. is being maintained the-greater the reduction .of 7 pressure on the heated stream ofjwater when said water is discharged into the flash chamber F' from the generator coils .G1 and G2. The'higher the. pre-, determined pressure under which the water contained in the. water storage pressure tank T is bein imaintained the higher the heatcontentofbefore, the connection is now adjusted .to vary the ratio of steam'to excess unvaporized water separatedin the flash chamber F. 7

The combination of rates of dischargefof the heated stream oiwater into the flash chamber F and the ratios of steam to excess unvaporiz'ed water capable to being separated in .the flash chamber F and the variations thereof are in finite in number. Suflice it to say that the best combination depends on the particular service for which thesteam boilerfis intended;

. The third principleofbpera'tion the'refore is tovary the rate of discharge of the heated stream of water flowing fromithe generator'coils G1 and G2' into the flash chambe'r F and {also vary the ratio of steam'to excess unvaporized watersepa rated in the flash chamber F to separate sufficient steam therein to meet a varying steam demand and maintain the desired pressure in the 'flash chamber F. I No matter on which principle the steam boil-er isopera'ting the stream of water being heated in thegenerator coils, G1 and G2 is being forced therethrough under the constant predetermined pressure from the water storage pressure tank T. Therefore, 7 the variations of pressure under which the water is;be ing' heate d in the generator coils G1 and G2 are very small which tends to prevent uncontrolled ebullition of thewater in the generator coils G1 and G2 due to the reduction of the pressure thereon. 7

Once the. desired; pressure to be maintained in the flash. chamber F .isknown', this desired the water being heated in the generator coils G1 and-G2 can be raised without ebullition therein.: In general the higher, the predetermined pressure under which the water contained in the water-storage pressure tank T is being main tained'the dryer the steam :being separated in the flash chamberF. For certain operating conditionsthe steam beingseparated in the flash chamber F can contain various degrees of superheat. It is to be noted that the pressure under which the stream of water is heated inthe gen erator coils G1 and G is, except as influenced by friction, substantially the same as the pre determined pressure under which the water contained in the Water storage pressure tank T is being. maintained. Therefore, the quality of the steam being separated in the flash chamberF is controlled by the predetermined pressure under which the Water contained inth'e waterv storage pressure tank T is beingmaintained which is substantially the same. pressure under which the stream of water is being heated in the generator coils G1 and G2.

There are several safety devices which remove operationalhazards and contribute to the prac: tical operation of the steam boiler These devices are explained in the following part of the specificati on. A device e actuated by and responsive to pressure inthe flash chamber. F and connected there: to is operatively connected. with the throttling type controlvalveI-I. The device e is set to oper ate when the pressure in the flashlchamber F reaches a predetermined low pressure, lower than the desired pressure being maintained in the flash chamber F. When the pressure in the flash chamber F drops to thepredetermined low pressure for which the device e is set, the latter causes thethrottling type control valve H to shut ofi automatically the heated stream of water flowing from the. generator coils G1 and G2 into the flash chamber F and at thesame time causes con; trol valve M to shut oil" the fuel oil supply to burner L and thereby stop the'heat input to the gen-. erator coils G1 and G1. Device e takes precedence over the pressure operateddevice h. and once set in operation device 6 must be reset before the steam boiler can again be placed in operation. Thepurpose of the device els to stop the heat input to the'generatorcoils.G1 and G2 and to cut off the flow of water being discharged into the flash chamber F through the throttling type control valve ,Hv gin the ;.,event of anaccidental r bre'ak in thesteam' iines to prevent injury to the generator fcoils Gr and Gil-Device 6 can beany 7 low limit pressure cutoutwith manual reset, one

' suitable"type-*being--such =as= manufactured by the Brown instrument Co. 1 In the-pipeIin-e 2 -there is *acheckvalve R2. The purpose of-the checkva1ve R2 is to-prevent reverse-flow of the stream of water in this pipeline in theeyent theipressure in the flash chamber F should accidentally increase above the pres- '1 surerunder'::whichatheestream Off-" WateI is. being heated in the generator coils G1 and G2 in-which case the waterhwould berforcedput of the genhe watencon-tained inthei -iwater storage pressure tank- T -f-romflowingeback.through.the pump B when thelatter is note-operating, and flooding r the flash chamber F with water.

'- R1- is a checkvalve 'to =prevent the water "contai-nedin the-waterstorage=pressure tarikT from flowing back through the pump A when the latter is not operating.

S1 is a safety valve connected to the water storage pressure tank T. S2 is a safety Valve connected to the pipeline 2. S3 is a safety valve connected to the flash chamber F. Each one of these safety valves is set to release excessive pressure and prevent bursting of the vessel or pipe to which it is connected if the pressure therein accidentally increases excessively.

On starting the steam generating boiler the following procedure may be used. The control valve H is closed. Then pump A is started and keeps running until the required pressure is reached in tank T at which time the pressure control device a stops operation of pump A. Then control valve H is opened slightly and cold water from generator coils and tank T falls into bottom of flash chamber F where pump B automatically removes it to water storage pressure tank T (as shown in drawing). After this cycle is begun the oil burner L is put in operation and begins to heat the water in generator coils G1 and G2. The heated water reaches control valve H, separates into steam and excess unvaporized water in flash chamber F and as soon as the desired steam pressure in flash chamber F is reached the valves H and M and pumps A and B work automatically to maintain the pressure in flash chamber F as constant as possible.

On shutting down the steam generating boiler the following procedure may be used. The fuel supply control valve M is closed so that no more fuel is burned in oil burner L. The water in generator coils G1 and G2 is no longer heated and as soon as cold water reaches control valve I-I no more steam is separated in flash chamber F. The pressure is flash chamber F falls and pressure control device e automatically closes valve H to the predetermined minimum rate of discharge and stops the heat input to the generator coils G1 and G2 after which power to pumps A and B may be shut off.

My invention is characterized in that: (a) the forced circulation of water over the heating surface of the boiler (through generator coils) can be increased according to the percentage of water Which is unvaporized in flash chamber; (b) the quality of the steam may be changed without the use of additional devices; the flash chamber, or chamber from which the steam is drawn, can

The purpose ofthe-:checkvalve R3 .is to prevent -be-placed at anypracticaldistance or level,' either above or below-y away from the heatingsurface (generator coils); (d)' -tl '1'e----boiler is economical to build,=- canbe made compacti-arrd"due to the methodused to-control the-forced -wate'r circulationand-fuel burned or supplied, is very flexible and highly efiicient.

T11 Inthe'speciflcation'above-and the claims which i' ifo-llow leelow, it is to be: :notedthat my invenationisinotrdependent for. its.operation on the boil- :a: er aliquideused'lrMy =inventionwillpperate using anyisuitable, liquid inwtheaboilersuch asacan be used m an-y conventional -typesboiler to generate .steam or to generate-vapor of: the liquid used.

15. Ieclaim:

g 1..,A .stea ngeneratingmoiler,apparatus orsunit comprising igenarators, heating water. flowing under a vsubstantially constant predetermined pressure means. v for controlling the heat, input to said'generat'o'r to produce steam, aflash chami said flash chamber continuously discharging said steam andwaterto the lattei'ythe'flash chamber being 'under "a -substantiallyconstant predetermined pressure whichis lower than that in said generator and separating said steam from water still contained therein, a throttling type control valve in said conduit to regulate the rate of discharge of said steam into said flash chamber, means connecting said heat input controlling means and said throttling type control valve, means responsive to pressure in the flash chamber to automatically control said heat input means into the generator and regulate said throttling type control valve, a steam conduit extending from said flash chamber, a water tank having an air chamber communicating therewith and being under substantially the same constant pressure as said generator, a second conduit connecting said water tank with said generator and a third conduit for removing said water from said flash chamber to said water tank, a first pump means in said third conduit, means responsive to the level of said water in said flash chamber to automatically control said first pump means in order to maintain a predetermined level of the water in said flash chamber, a feeding conduit including a second pump means for feeding water into said water tank, and means responsive to the pressure in said water tank to automatically control said second pump means, thereby maintaining substantially constant pressure in said water tank.

2. A steam generating boiler apparatus or unit comprising a generator heating water flowing under a substantially constant predetermined pressure, means for controlling the heat input to said generator to produce steam, a flash chamber separating said steam produced in said generator from water still contained therein at a predetermined substantially constant pressure which is lower than that in said generator, a first conduit from said generator to said flash chamber continuously discharging said steam and water into the latter, a control valve in said conduit controlling the rate of discharge of said steam and water into said flash chamber, means responsive to the pressure in the flash chamber to automatically control the heat input to the generator by operative connection between said pressure responsive means in the flash chamber and said means for controlling the heat input to said generator and to maintain the predetermined substantially constant pressure in said flash chamber while steam is being withdrawn thereber. and a. first conduit from 'said'generator to from, a steam conduit extending from said flash chamber, awater tank having an air chamber communicating therewith being under substantially the same constantpressure as said generator, a second conduit connecting said water tank with said generator, and a third conduit for removing water from the flash chamber to said water tank, a first pump means in said third conduit feeding water under predetermined pressure from said flash chamber to said water tank, means responsive to the level of said water in said flash chamber to control said first pump means in order to maintain a predetermined level in said flash chamber, a feeding conduit including a second pump means for feeding feed water a into said water tank, and means responsive to pressure in the water tank to automaticallycontrol said second pump means so as to maintain substantially constant predetermined pressure in said water tank.

3, The apparatus, as set forth in claim 2, in which said control valve is adjustable and includes means for feeding the steam and water file of this patent:

- of difierent constant rates of discharge.

4. The apparatus asset forth in 'claim 2, in which said control valve has an orifice permitting of discharging said steam and water into said flash chamber at a substantially constant predetermined rate of discharge. 4

- JOHN MARINI.

REFERENCES CITED I The following references are of record in the UNITED ELTATES PATENTS Number Name 774,312 Dodge Nov. 8,-1904 2,049,652 Jolley Aug. 4, 1936 2,200,471 Dickey t. May 14, 1940 2,227,349 Kerrick Dec. 31, 1940 20 2,276,624 Oeltjen Mar. 17, 1942 FOREIGN PATENTS 7 Number Country Date 231,142 Great Britain May 13, 1926 

